OK, I am running 2002. It has Task Panes as well. Yes, only one can be shown at a time.
Ctrl-F1 must be new to 2003 to call a Task Pane. It does not do so in 2002.
There is very minimal exposure to the Task Panes, programatically speaking. You can add certain items to the NewDocument Task Panes, but:
you can not edit the builtin items.
you can not, as far as I know, create a new custom Task Pane
If you have a form with controls, why do you want it to be in a Task Pane? I do not understand what advantage this may bring. Why not just call up your form. Heck, you can even make non-modal so it floats independently.
However, unless 2003 has changed significantly, you can not create a new Task Pane. There is no Add method to the collection; there is no .Delete; there is no .New.
As I mentioned, other than the .Visible property, and being able to .Add items to the New Document Task Pane, there is not much you can do with them in VBA.
Gerry